The present invention relates to a humidifier suitable for use in automotive air conditioning.
Hitherto, various inventions have been achieved in connection with humidifiers and some of them have been carried out commercially. One of these known humidifiers has a water tank and an electric heater or a burner for heating the water in the tank thereby to produce steam. This type of humidifier will be referred to as "water tank type humidifier", hereinafter. Another known humidifier is adapted to directly inject steam of high temperature and pressure into air. This type of humidifier will be referred to as "steam type humidifier", hereinafter. Still another known humidifier employs an ultrasonic vibrator adapted to generate fine particles of water. This type of humidifier will be referred to as "ultrasonic humidifier", hereinafter. A further known humidifier incorporates a heat exchanger for heating air, onto which water is sprayed or dripped to become steam. This type of humidifier will be referred to as "spray type humidifier", hereinunder. Thus, various types of humidifiers have been produced and sold commercially.
Among these known humidifiers, the water tank type humidifier is not suitable for use on automobiles because it cannot operate stably due to the vibration during running of the automobile and because it requires a heat source of a large capacity. The steam type humidifier also is not suitable because it necessitates separate steam generating equipment such as a boiler. Clearly, these two types of known humidifiers are unsuitable for use on automobiles. The ultrasonic humidifier is also unsuitable because it produces mist-like steam to excessively wet the compartment and passengers and to restrict the sight of the driver. In addition, it is necessary to use an oscillation circuit which is generally expensive.
The spray type humidifier is free from the problems stated above. In addition, the known warm water type heater used in automotive air conditioning can be used advantageously as the heat exchanger. In this case, however, air has to be heated simultaneously with the humidification. Thus, this type of humidifier can suitably be used only when the air is humidified in the heating mode, but cannot apply to the case where the air has to be cooled down simultaneously with the humidification.